Broaching apparatus



July 27, 1954 J. A. PSENKA ETAL 2,684,612

BROACHING APPARATUS Filed Oct. 22, 1951 2 Sheets-Sheet 1 3 l P? I L i II FLI-l: l

I I l I &.

:a P II 1 1 a 5 H INVENTORJ MW, r 617% ATTORNEYS July 1954 J. A. PSENKAETAL BROACHING APPARATUS 2 Sheets-Sheet 2 Filed Oct. 22, 1951 INVENTORSflaw TO R N E Y 5 Patented July 27, 1954 UNITED STAES ATE? a en BROACHING APPARATUS Michigan Application October 22, 1951, Serial No. 252,514

((31. Bil-33) 3 Claims.

The present invention relates to breaching apparatus and moreparticularly to apparatus effective to permit rapid breaching ofportions of holes in a succession of work pieces.

One of the troublesome features of breaching holes in work pieces isthat it is normally necessary to disconnect the breach from the breachpulling head after each Work piece is broached, to permit mounting a newwork piece on the machine or to thread the part over the breach, as inthe case of a keyway pull breach. In the present case the machine isdesigned for breaching only a portion of the holes of a succession ofwork pieces and accordingly, it is made possible to carry out thebreaching operation in an extremely rapid manner without the necessityof disconnecting the breach from the breach pulling head.

In general terms this is accomplished by supporting the work piece on ahorn having a longitudinally extending recess at one side thereof, inwhich recess the breach is both longitudinally movable, and movableinwardly and outwardly of the recess, or at right angles to thelongitudinal movement. Cam means are provided which permits the breachas it approaches the free or unsupported end of the horn, to moveinwardly of the recess to a clearance position which permits loading thework piece over the horn and breach without interference. Thereafter, asthe breach is drawn longitudinally in a direction toward the supportedend of the horn, cam means intermediate the horn and breach, cam thebreach outwardly of the recess to cutting position. The breach is thendrawn completely through the work piece or at least to a final cuttingposition, in which the last teeth of the breach clears the work. In theevent that the breach is not drawn completely through the work piece,the cam means permits movement of the breach inwardly oi the recess uponcoropletion of the cutting stroke. In either case the completed workpiece may then be freely withdrawn from the horn without interference.

It is an object of the present invention to provide breaching apparatusfor breaching portions of holes in work pieces in a rapid and eflicientmanner.

It is a further object of the present invention to provide breachingapparatus which permits loading of a succession of work pieces without rthe necessity for disconnecting the breach from the breach pulling head.

It is a feature of the present invention to provide a work supportinghorn having a longitudinally extending recess along one side thereof, a

breach in the recess movable both longitudinally therein, and inwardlyand outwardly of the recess, together with cam means for controlling thelast mentioned movement of the breach.

Other objects and features of the invention will become apparent as thedescription proceeds, especially when taken in conjunction with theaccompanying drawings, wherein:

Figure 1 is a perspective View of the breaching apparatus.

Figure 2 is a plan View with parts broken away of the breachingapparatus.

Figure 3 is a side elevation of the breaching apparatus with partsbroken away and with parts in section.

Figure l is an enlarged end view of the breaching apparatus as seen fromthe right in Figure 2.

Figure 5 is an elevational view of the work piece showing the workperformed by the present apparatus.

Figure 6 is an enlarged fragmentary sectional view showing the camportions of the horn and breach.

The breaching apparatus illustrated in Figures 1-4 is particularlydesigned to carry out a breaching operation in which a work piece has ahole therein, on which a breaching operation is to be carried out whichoperates over less than the entire inner surface of the work piece. Sucha work piece is illustrated in Figure 5 where the piston P is shown ashaving a through opening it in which the breaching operation is tobreach a series of grooves or serrations i2. Inasmuch as the breachingoperation operates only on a portion of the inner circumference of thehole ill, it is possible to support the work piece P in a novel mannerso that separation between the breach and. the breach pulling head isnot required.

Referring now specifically to Figures 1-4 the breaching apparatuscomprises a base it having an upstanding bracket is carrying a powercylinder indicated generally at it. Located within the cylinder it is apiston (not shown) connected to a piston rod 253 which in turn at itsouter end is connected to a breach pulling head 22.

The base is is provided with a second upstanding bracket 25, to which issecured a work supporting fixture it and a work supporting and breachreceiving born 28. Extending between the brackets 56 and 24 are a pairof guide rods Ed on which the head 22 is longitudinally slidable.

Referring now specifically to Figure 3 the horn 28 is provided with alongitudinally extending recess 32 which extends completely to thesupported end of the horn but which is closed by a head portion 34 atthe free or unsupported end of the horn. The recess could extendcompletely to the free end of the horn, but the illustrated arrangementis preferred since it increases strength of the horn, improves ease ofloading and prevents marring the work. The bottom wall of the reces 32constitutes a cam surface which cooperates with a broach 3t and for thispurpose the bottom wall of the recess 32 includes a camming step 33separating an elevated dwell portion at and a depressed portion 42. Atits inner end the horn 28 includes a generally semi-circular flange M5.The fixture 26 at its left hand side, as seen in Figure 3, has acircular recess iii which re ceives the semi-circular flange as withclearance, the flange locating against the adjacent surface of bracket2d. At its top the bracket 25. has a keyway therein and a correspondingkeyway 55 i provided in the top of tr e flange l i, as well as a keyway52 in the top of the fixture 25. A key 54 is received in the threekeyways d8, 53 and 52, and is secured in place by a screw Thus thefixture 25 and the horn are supported in properly aligned and accuratelymaintained position. The fixture as indicated in Figure 2, isadditionally supported by screws 53 extending into the bracket iii.

The broach pulling head 52, as best seen in Figure 3, is provided with arecess *3!) which receives the inner end of the broach 36. The broach isprovided adjacent its inner end with a down wardly open transverselyextending recess G2 which receives and partially surrounds a pivot pinGd. Thus the broach 3% is mounted for rocking movement inwardly andoutwardly of the recess 32 of the horn 28 about the axis of the pivotpin 64. In order to provide a force maintaining the body or cuttingportion of the broach 56 in contact with the bottom or upper surface ofthe recess 32, a compression spring Ed is provided, the lower end ofwhich engages the inner end of the broach 35 and the upper end of whichis received within a spring seat located in a threaded adjusting element68. Suitable means including operating buttons iii, are provided forcontrolling reciprocation of the broach pulling head 22, but theseconstitute no part of the present invention and accordingly will not bedescribed in detail.

With the parts in the position shown in Figure 3 it will be observedthat the broach 38 is located in its innermost position relative to therecess 32 in the horn 23, and that a carnming shoulder F2 on the broachis located outwardly or to the right of the inclined step 38 at thebottom of the recess 32. With the broach and horn in this relativeposition it is possible to advance the work piece P to the positionshown in dotted lines in Figure 3, at which time it is received withinthe concave portion I i of the fixture 25 and is properly locatedtherein by engagement between the horn 2S and the hole in the workpiece. At this time fluid is admitted to the motor or power cylinder ISin a direction to move the broach pulling head 22 to the left. Initialmovement of the broach to the left causes the inclined camming portionl2 of the broach to ride up on the inclined step 38 at the bottom of therecess 32, thus moving the broach downwardly, or outwardly with respectto the recess, into cutting position. The cutting operation takes placeas the broach moves to the left, and if desired, the broach may becompletely withdrawn from the work piece after which the work piece ireadily withdrawn from the horn and replaced by a second work piece. Ifpreferred, it is unnecessary for the broach to be moved completely outof the work piece since if desired, the bottom wall of the re cess 32may be shaped to permit retraction of the cutting portion of the broachinto the recess after the last cutting tooth has cleared the work. Forthis purpose the dwell portion at the bottom of the elongated recess inthe horn may terminate a indicated at "it. With this arrangement thebroach is retracted into the recess in the horn at both ends of itscutting stroke and is cammed outwardly only during the intermediateportion of its cutting stroke. In either case, upon completion of thecutting stroke the broach is in a position in which it does notinterfere with removal of the work piece and the work piece may bewithdrawn without again contacting the broach. Alternatively of course,it would be possible to return the broach to the position illustrated inFigure 3 before removing the work piece but this would involve drawingthe cutting teeth of the broach rev-ersely over the broached surface,which is undesirable.

The drawings and the foregoing specification constitute a description ofthe improved broach in such full, clear, concise and exact terms as toenable any person skilled in the art to practice the invention, thescope of which is indicated by the appended claims.

What we claim as our invention is:

1. Broaching apparatus comprising a frame part having a machinedlocating surface thereon, a horn having a free end and a supported endprovided with a laterally extending flange, said flange having alocating surface engageable with the locating surface of said framepart, a work supporting and locating fixture having a locating surfaceengageable with the locating surface of frame part having a recess inwhich the flange of said horn is received, aligned keyways in said framepart, said flange, and said fixture, a key in. said keyways, said hornhaving an elongated recess extending from its supported end to the otherend thereof, a broach reciprocable in said recess, resilient meansurging said broach inwardly of the recess in said horn to a clearanceposition which permits a work piece to be loaded and. unloaded over thefree end of said horn, cam means between said broach and horn operableto shift said broach outwardly of said recess to cutting position uponinitial movement of said broach longitudinally of said horn toward thesupported end thereof, and means for traversing said broach in a cuttingstroke toward the supported end of said horn and an idle return stroketoward the free end of said horn.

2. Apparatus as defined in claim 1 in which said cam means is shaped toprovide for inward movement of said broach to clearance position at bothends of its stroke.

3. Broaching apparatus comprising a frame having an upstanding portion,said portion having a horizontally extending opening therethrough, ahorn extending from one side of said portion, said horn having anelongated recess therein in re istry with the opening through saidportion, a broach extending through said opening and at least partlyreceived in said recess, motor means on said frame spaced horizontallyfrom frame portion, horizontal guide elements extending between saidmotor means and said frame portion, a cross head on said guide elements,means connecting said cross head to said motor means, said cross headhaving a recess therein receiving an end of said broach, pivot meanswithin said last recess engaging said broach, a spring in said recesshaving one end engaging said broach at a point spaced from said pivotmeans to bias said broach inwardly of the recess in said horn, and camsurfaces on said horn and broach effective to cam said broaeh outwardlyof the recess in said horn into cutting position upon initial movementof said broach in a cutting stroke.

References Cited in the file of this patent UNITED STATES PATENTS NumberNumber Number 10 368,757

Name Date Ruedy Aug. 14, 1906 La Pointe July 17, 1917 Andrews July 6,193 Hoagland Sept. 28, 1943 Markstrum Jan. 29, 1946 FOREIGN PATENTSCountry Date Great Britain Mar. 8, 1932

